Your face changes because skin collagen falls with oestrogen, fastest in the first years around the final period, while fat pads thin and dry skin reflects light unevenly. That is why it reads as a change in shape rather than a new line. Sun damage decides how much of it shows.
Collagen is the scaffolding, and its loss is the main event in ageing skin. There is a strong correlation between skin collagen loss and oestrogen deficiency after menopause, and clinical references describe the loss as rapid in the first five years. That is why women so often say it happened in a year: the change is real, it is measurable, and it is front-loaded rather than spread evenly across a decade.
Three things move at once and they read differently in the mirror. Collagen and elastin loss changes how skin holds its shape, so the jawline softens before any new line appears. The fat pads that sit under the cheek thin and drop, which changes the shadows on your face more than the surface does. And skin that holds less water has a rougher surface, which scatters light instead of reflecting it evenly, so it reads as dull even when nothing else has changed.
Sun exposure decides how much of this you see, and it is the part you have most control over. It is also the reason the obvious idea does not work: in a controlled trial, 24 weeks of topical oestrogen on the faces of post-menopausal women did not improve wrinkles or elasticity at all, and it raised the enzyme that breaks collagen down more than tenfold. The blunt reading is that a sun-exposed face does not answer a hormone you put on it, and that sunscreen is doing more work than any bottle in the cabinet.
The usual causescollagen falling with oestrogenfat pads thinninga rougher, drier surfaceyears of sunsleep that broke firstless protein than the body is asking for